The practice was condemned by Kevin Green, the chief executive of the Recruitment and Employee Confederation (REC).

“Clearly it is wrong to accept discriminatory instructions and we expect all our members to challenge any such request from employers,” said Green. “Even in these tough economic times, we would expect our agencies to walk away from the business – that’s how seriously we take the issue of discrimination.

However, Green denied claims that the practice was commonplace across the country.

“Any perception that the majority of agencies are colluding with employers is wide of the mark,” he said. “What this programme does show though is that clear leadership and appropriate staff training is essential so that consultants at even the most junior level have the confidence to challenge any employers who make discriminatory requests.”

A spokesman for the Department for Work and Pensions, which oversees Jobcentre Plus, told Personnel Today it was still confident in working with REC members despite the results of the investigation.

“Discrimination on the grounds of colour or race is against the law and we would expect companies and suppliers we work with to adhere to the law,” he said.

“As an employer we are committed to equality and diversity within our workforce. Staff and managers are aware of their responsibility to maintain these standards in all aspects of our day-to-day work.”